1. Field of the Invention
The present invention relates to lateral flow test strips and methods of operation for the lateral flow test strips.
2. Description of Related Art
Quantitative analysis of cells and analytes in fluid samples, particularly bodily fluid samples, often provides critical diagnostic and treatment information for physicians and patients. For example, immunological testing methods which take advantage of the high specificity of antigen-antibody reactions, provide one approach to measurement of analytes. Kennedy, D. M. and S. J. Challacombe, eds., ELISA and Other Solid Phase Immunoassays: Theoretical and Practical Aspects, John Wiley and Sons, Chichester (1988). This document and all others cited to herein, are incorporated by reference as if reproduced fully below. Such assays may also find use in various other applications, such as veterinary, food testing, or agricultural applications.
Immunoassays that provide a quantitative measurement of the amount of an analyte in a sample have previously used complex, multi-step procedures and expensive analyzers available only in a laboratory setting.
Immunochromatographic assays, such as those described in GB 2,204,398A; U.S. Pat. Nos. 5,096,837, 5,238,652, and 5,266,497; Birnbaum, S. et al., Analytical Biochem. 206:168-171 (1992); Roberts, M. A. and R. A. Durst, Analytical Chem. 67:482-491 (1995); and Klimov, A. D. et al., Clinical Chem. 41:1360 (1995), are simpler, yet do not provide a quantitative measurement of an analyte. Instead, these immunochromatographic assays detect the presence (or absence) of an analyte above a defined cutoff level for the test performed. The lack of a quantitative measurement limits the usefulness of these assays.
A variety of disposable diagnostic assay devices have also been developed. Examples of such devices include, but are not limited to Cathey, et al, U.S. Pat. No. 5,660,993; International Publication Number WO 92/12428; Eisinger, et al, U.S. Pat. No. 4,943,522; ;Campbell, et al, U.S. Pat. No. 4,703,017; Campbell, et al, U.S. Pat. No. 4,743,560; and Brooks, U.S. Pat. No. 5,753,517. Nevertheless, a need still exists for improved disposable diagnostic assay devices and methods.